We examine the ways in which nebular observations of He II lambda4686 can be used to infer the existence of coronae or hot winds of early-type stars. The O VI lambdalambda3811, 3834 doublet is seen in the spectra of some central stars of planetary nebulae, and several authors have considered this to be evidence of a coronal wind. Observations of NGC 6751 reinforce this view by showing that radiative equilibrium model atmospheres cannot sufficiently photoexcite the O VI transitions without producing too much nebular emission at lambda4686. The hot gas in the coronal model produces a significant amount of radiation at energies above 54 eV; therefore, the He II Zanstra temperatures can be affected. Discrepancies between the He II Zanstra temperatures and effective temperatures derived from other methods may indicate coronal emission from planetary nebula central stars.Observations of diffuse nebulae about Population I early-type stars may also prove useful in detecting hot winds. The Lamers and Morton model of the wind of the O4f star xi Pup predicts a small amount of He/sup +/ ionizing radiation. If NGC 7635 is associated with the Of star BD +60/sup 0/2522, then the observation of nebular emission at lambda4686 may indicate coronal emission.